The present invention relates to an ISDN (integrated service digital network) terminal system used in connection with an ISDN.
Em an ISDN exchange method, there exist two modes, line exchange and packet exchange. In the conventional ISDN terminal system, only one of the above two exchange modes can be used. Therefore, there exists a problem in that the terminal system can communicate with only the terminal systems using the same exchange mode, and cannot communicate with those of a different exchange mode.